In today's communications industry rapid advances in communication protocols and techniques are common. To facilitate widespread deployment of new systems, significant efforts are often made to ensure new communications techniques and systems are compatible with previous systems and devices, referred to herein as “legacy” systems or devices.
Throughput above the Medium Access Control (MAC) level is a key parameter of wireless local area networks (WLANs). One way to get more throughput is to use longer frames in the air link that decreases overhead of headers and inter frame pauses. Such a long frame could be built as concatenation (or aggregation) of MAC level Protocol Data Units (MPDUs) and sent as a single Physical Protocol Data Unit (PPDU). However in legacy WLANs only one MPDU per PPDU is allowed.
Longer frames proposed for newer generation systems may cause problems for interoperability with legacy systems as techniques typically used for avoiding collisions in legacy systems may not be designed to accommodate the longer frame transmissions of newer generation systems.
Accordingly, a system which provides longer frame capability and reduces frame collisions would be desirable.